Windows are an essential source of natural light and ventilation for your home. As they are openings to the outside, they can also be significant sources of heat loss, especially in older or poorly insulated buildings.


When homeowners choose to install secondary glazing, they will benefit from reduced heat loss as the glazing acts as an additional layer of insulation that improves the home’s overall energy efficiency. But how you can reduce heat loss and how can secondary glazing help you save both energy and carbon emissions?

How Much Heat is Lost Through Old Windows?

The average home loses up to 18% of heat through windows as a consequence of it being poorly insulated or only single-glazed. It can also be typically caused by radiation, convection or conduction.


  1. Conduction is the transfer of heat through a material when there is a temperature difference between the two sides of it. In windows, heat is conducted from the inside of the building to the outside through the glass and frame. Single-glazed windows in particular are very conductive and can allow a large amount of heat to escape.


  1. Convection is the movement of air currents around a building and in windows, which can create cold spots that cause heat loss. When warm air comes into contact with a cold window surface, it cools, becomes denser, falls to the ground and creates a draft. This draft brings cold air into the room and constantly repeats itself so further heat is lost.


  1. Radiation is the transfer of heat through electromagnetic waves. In windows, radiation occurs when heat from the inside of the building is absorbed by the glass and re-emitted to the outside. Low-emissivity (low-E) glass can reduce radiation by reflecting heat back into the room.

Can Secondary Glazing Stop Heat Loss?

Secondary glazing products are suitable for all property types, especially for those looking to insulate drafty old or single-glazed windows. The added layer of protection offered by secondary glazing on top of your windows will ensure that any heat remains firmly within your home rather than outside.


With secondary glazing, you will reduce up to 60% of heat loss meaning you do not need to use as much energy on heating your home on colder days and nights. In turn, it will also reduce your carbon footprint as you won’t need to rely on your central heating as often.

How Can You Make Your Home More Energy Efficient?

An easy way to improve energy efficiency in your home is by fitting secondary glazing. Secondary glazing is made from a Low-E glass system which contains a reflective coating that diverts heat back into the room. It additionally has an added 8mm air-filler cavity to improve heat retention and reduce your home’s energy consumption.


Secondary glazing will also improve your Energy Performance Certificate (EPC) rating and bring in long-term energy cost savings across cold and warm months. Your home will keep warm during the winter and cool during the summer therefore helping you to stay energy efficient no matter the weather.


With less need for turning on expensive heating, secondary glazing will help you save up to £105 off your energy bill. An example of this was seen by a previous customer who had installed secondary glazing in their single-glazed apartment, which resulted in dropping their monthly energy bills from £450 to £230 – an overall saving of up to 40%! Overall, secondary glazing is an excellent solution for reducing heat loss and making your home an energy-saving, breathable and comfortable living space.

Energy Savings Calculator: How Much Money Could you Save?

With energy bills not predicted to fall until the summer months, it’s important we find ways to reduce heat loss and energy consumption so our energy bills can lower in the months ahead.


Granada Secondary Glazing have created a helpful tool to accurately calculate how much money they can save with our secondary glazing products. Whether you’re looking to fit secondary glazing on a single window or across the whole building, you can easily use our calculator to find out how much energy you could save per day and annually in both summer and autumn. Try their energy saving calculator out today and find out how much energy you can save!


Cornwall Glass is Granada Secondary Glazing’s selected supplier and installer of secondary glazing throughout the Southwest. With branches from Penzance to Bristol we have the entire region covered!


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